Child-resistant packaging of drugs has been long available to the pharmaceutical industry. Such packaging has typically introduced impediments to gaining access to the packaged drug by children while providing access to the drugs to adults who are able to follow instructions for manipulation of the package in a manner that is not too difficult, yet which will deter opening by children.
Tablets have been individually blister packaged in a variety of child-resistant packages which have met with some degree of success and acceptance in the market place. Exemplary of one type is the so-called "Peel-push" concept of child-resistant packaging in which tablets are contained in individual flexible blisters sealed by a rupturable foil material, access to which tablets are selectively obtained by peeling off a protective layer to expose the rupturable material and to permit the tablet to be pushed through the rupturable material by pressure on the blister. Examples of commercially acceptable packages having such a "peel-push" feature are illustrated in U.S. Pat. No. 4,125,190 and U.S. Pat. No. Re. 29,705.
There has been a need for an all paperboard package utilizing "peel-push" child-resistant opening. However, heretofore such packaging has not been available to the pharmaceutical packaging industry. It is to the development and provision of a method of making such a "peel-push" paperboard package and the resulting package itself to which the present invention is directed.
The design of a "peel-push" package shown in U.S. Pat. No. Re. 29,705 involves the use of paper/foil or plastic/foil lamination where the paper or plastic surface is pealed back and the product is pushed through the foil once it is exposed. (However, this construction does not provide the aesthetics of a paperboard blister card.) Users of such packaging who desire to incorporate this concept into a paperboard blister card have been limited to a single option; namely, trap sealing a paper/foil/plastic packette into a paperboard card. The design shown in the U.S. Pat. No. 4,125,190 uses a continuous perforation on the back of the paperboard blister card which is only sealed to the outer edge of the foil and is opened by pulling back the perforated tear opening strip. However, the design utilizes a backing sheet which traps a preformed plastic foil package and does not provide a positive seal to the entire inner side of the foil. Moreover, with the designs shown in both of the aforementioned patents, once the top substrate has been peeled back to expose the rupturable foil, the product may be removed from the blister by pushing or collapsing any part of the flexible plastic dome or blister.
In accordance with the principles of the present invention, the shortcomings of the aforementioned constructions have been overcome through a new and improved manufacturing process and package design. Specifically, the incorporation of a "peel-push" child-resistant feature into an all paperboard card has been made possible by the manufacture of a paperboard product which may be readily peeled from both plastic and foil. In accordance with the concepts of the present invention this has been accomplished by applying peel/seal coating systems known for paper and lidding stock in the medical device field to a non-corona treated polyethylene coated paperboard. The use of non-corona treated polyethylene coated paperboard is very important, since corona treated polyethylene boards promote sealability in contrast to the characteristics of non-treated board, i.e., non-treated board prevents fiber contact with the coating and helps facilitate the "peel-seal" characteristics desired.
Moreover, in accordance with the principles of the present invention the comparative ease of removing a product by collapsing any part of the entire flexible dome of the thermo-formed blister, thereby limiting the degree of child-resistance, is overcome by removing only a portion of the paperboard closing off the bottom of the blister or only a fraction of the area of the dome. By only exposing a portion of the total covering of rupturable material of the dome opening, removal of the tablet requires specific selective pushing on the dome on one side only to expel the packaged drug. This makes it much more difficult for a child to remove the product by chance by pushing any portion of the dome. Rather, a selectively focused push on a specific portion of the blister, rather than on any portion, is required to gain access.
The new method by which the board stock for such a new package is manufactured involves scoring and die cutting the paperboard prior to laminating the foil. Current manufacturing techniques for "peel-push" stock do not permit independent paper die cutting from existing paper/foil lamination since the paperboard and the plastic are laminated together prior to die cutting, making it impossible to die cut the lid stock separately. Thus, in accordance with the principles of the present invention, the paperboard is die cut prior to its being laminated to the foil, the die cutting being to the specific configuration required to provide only limited exposure of the rupturable dome sealing material. The employment of this particular method of die cutting before foil lamination will enable improvements in "child resistance" to be made to many existing "peel-push" package designs.
For a better and more complete understanding of the present invention and a better appreciation of its attendant advantages, reference should be make to the following detailed description taken in conjunction with the accompanying drawings.